Finally, a great feature, that hasn't been mentioned here, is pandoc filters. Basically, pandoc provides a way for scripts (in any programming language) to hook into the transformation pipeline and modify the document AST (similar to the HTML DOM) in-between the reading and writing steps. See http://pandoc.org/filters.html

IRC channels and mailing list are excellent for informal questioning about a project. You can search for guidance, see if a feature would be well received, and receive a green light before starting to implement something.

Other day I thought about contributing to Yarn, the Javascript package manager, but the only way that I found to communicate with the developers were issues in GitHub. Since I didn't know if the feature I wanted would be well received, I just quit.

Have a look at Firefox Multi-Account Containers. You can open a tab that has a different color, and it uses a different cookie database. Very useful, because you can create an extra Github account and quickly switch between those accounts.

Hey, just a one-time contributor here (fixed a small bug in the wikitext parser), I have to say that the community is really, really great! I had never done any haskell before, but with just a little guidance from the IRC channel (#pandoc on freenode), I was put on the right track and submitted my small PR, which was merged quickly.